Capacitive sensor assembly

Abstract

A capacitive sensor assembly for a motor vehicle for detecting seat occupancy is provided. The capacitive sensor assembly includes a capacitive sensor element which has at least one first electrical conductor element, and an electrical heating element which has at least one electrically operated heating conductor and which is interspaced from the first electrical conductor element. The first electrical conductor element is designed as an external conductor surrounding the heating conductor.

The invention claimed is: 
     
       1. A capacitive sensor assembly for a motor vehicle comprising:
 a capacitive sensor element, which comprises at least one first electrical conductor element, the capacitive sensor element being configured to be connected to an evaluation unit, which detects and evaluates at least one measured value in dependency on the capacitive coupling of the capacitive sensor element to the surrounding, and 
 an electrical heating element, which comprises at least one electrically operated heating conductor and which is spaced apart from the first electrical conductor element, 
 wherein the first electrical conductor element is designed as an external conductor element which surrounds the heating conductor as an internal conductor, and 
 wherein a second conductor element extends between the first conductor element as the external conductor element and the heating conductor as the internal conductor. 
 
     
     
       2. The sensor assembly according to  claim 1 , wherein the first conductor element completely surrounds the heating conductor as viewed in a cross-sectional plane of the sensor assembly, which extends perpendicular to and intersects the first conductor element and the heating conductor. 
     
     
       3. The sensor assembly according to  claim 2 , wherein the first conductor element surrounds the heating conductor in the cross-sectional plane of the sensor assembly, which extends perpendicular to and intersects the first conductor element and the heating conductor, as a closed curve. 
     
     
       4. The sensor assembly according to  claim 1 , wherein the heating conductor and the first conductor element are spaced from each other as viewed in a cross-sectional plane of the capacitive sensor assembly that extends perpendicular to and intersects the first conductor element and the reference conductor element such that a line, which intersects the first conductor element and the heating conductor, is shiftable independently of the spatial orientation of the line in the cross sectional plane by parallel displacement in the cross-sectional plane in a direction orthogonal to the straight line into a position, in which said line forms a curve secant of the first conductor element without intersecting the heating conductor. 
     
     
       5. The sensor assembly according to  claim 1 , wherein the first conductor element as an external conductor element and the heating conductor as an internal conductor form a coaxial cable design. 
     
     
       6. The sensor assembly according to  claim 1 , wherein the first conductor element as an external conductor element and the heating conductor as an internal conductor form a shielded cable design. 
     
     
       7. The sensor assembly according to  claim 1 , wherein the second conductor element shields the first conductor element and the heating conductor against each other. 
     
     
       8. The sensor assembly according to  claim 7 , wherein the dielectric is compressible under pressure. 
     
     
       9. The sensor assembly according to  claim 8 , wherein the sensor mat serves as a heating mat for heating at least one vehicle component. 
     
     
       10. The sensor assembly according to  claim 1 , wherein the second conductor element is provided as a potential controlled shield. 
     
     
       11. The sensor assembly according  claim 1 , wherein the first and the second conductor element as well as the heating conductor form an n-axial cable design. 
     
     
       12. The sensor assembly according to  claim 1  wherein the heating conductor is at least partially surrounded by a dielectric. 
     
     
       13. The sensor assembly according to  claim 1 , wherein the heating conductor as a potential carrying element defines a reference potential. 
     
     
       14. The sensor assembly according to  claim 1 , wherein the first conductor is supplied with an alternating current and a measuring device for determining parameters of the alternating current is provided in order to determine the effect of the sensor assembly on the alternating current. 
     
     
       15. The sensor assembly according to  claim 1 , wherein the sensor assembly is part of a sensor mat. 
     
     
       16. The sensor assembly according to  claim 1 , wherein the sensor assembly forms furthermore a temperature sensor. 
     
     
       17. The sensor assembly according to  claim 1 , wherein the sensor assembly is designed and provided for assembly into a motor vehicle part in order to recognize herewith the presence of a vehicle occupant in a specific seat. 
     
     
       18. The sensor assembly according to  claim 1 , wherein the sensor assembly is designed and provided for assembly into a motor vehicle seat and/or a steering wheel and/or a safety belt system. 
     
     
       19. A motor vehicle seat with a seat frame, at least one seat cushion provided at the seat frame and a sensor assembly according to  claim 1 , which serves for recognizing the seat occupancy as well as for heating the seat cushion. 
     
     
       20. A motor vehicle steering wheel with a steering wheel body and at least one sensor assembly according to  claim 1  provided at the steering wheel body, which serves for recognizing the hand rest of a vehicle driver on the steering wheel as well as for heating the steering wheel.